The present invention relates to a remote image monitoring method and system for executing remote image monitoring with use of digitalized images of a TV camera, and to a recording medium for use in executing the remote image monitoring.
Remote image monitoring has conventionally been executed with use of TV cameras for many purposes and uses, for example, in order to monitor the operational states of equipment installed in various spots in plants, to check the entering in and exit from buildings of persons, and to confirm the possibility of danger.
When remote image monitoring is executed with use of TV cameras, TV cameras or objects to be controlled are installed on the spot side and a monitor apparatus is installed on a control room side, relatively near the objects to be controlled. Analog images of the TV cameras are displayed on the monitor apparatus via analog cables to constantly monitor the condition of the spot.
In the prior art, as mentioned above, the remote image monitoring in the control room is executed at all times. In recent years, however, it is desired for various reasons to execute monitoring with ease at locations other than the control room.
For example, it is desired that in preference for the health of monitoring workers or the comfort of working environment, the remote image monitoring be easily executed with use of personal computers, etc. at freely chosen places such as desks within offices or homes of monitoring workers. It is also desired, from the standpoint of reduction in personnel expenses of monitoring workers or in power consumption for monitoring, that the remote image monitoring be executed at night by a small number of monitoring workers with use of personal computers installed at a watchman room in a factory or accommodation facilities.
In order to achieve this, however, communication means suitable for remote image monitoring with use of TV cameras needs to be provided between the control room and monitor terminals. An example of conventional communication means is a network (Ether 10M, etc.). Specifically, there is an idea of using a TV meeting system in which a meeting is conducted while participants are viewing one another's image, by utilizing digital image distribution techniques available on the network.
However, the digital moving picture transmission executed in the TV meeting system is based on the digital moving picture compression system according to ITU-T-recommended H.261, wherein the image resolution of camera signals is "352.times.288" (in the case of CIF) or "176.times.144" (in the case of QCIF). The image resolution in this system is too low to be applied to the remote image monitoring in which the condition of the spot varies subtly due to a variation in environment.
As has been described above, the conventional system is merely applied in accordance with properties of communication media, and no special device is made. In addition, even if an existing network is to be applied to remote image monitoring, disturbance may be caused in the network and thus there is a problem the in application.
Under the circumstances, there is a demand for executing remote image monitoring with clear images, which can be executed in a freely chosen environment desired by monitoring workers at places other than the control room (e.g. desks within offices, homes of monitoring workers, branches, watchman rooms in factories, or accommodation facilities).